Aqueous Pretreatment for Offset Media Inkjet Printing
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Solution Overview
Problem
Aqueous inkjet inks face challenges when printing on offset coated media due to low ink absorbency and hydrophobicity, leading to non-uniform color deposition, increased drying time, and inter-color bleed, which results in image defects such as mottle and white streaks.
Innovation Solution
An inkjet printing fluid set comprising an aqueous pretreatment composition with an ink-aggregating agent and an ink-nonaggregating polymer, along with a surfactant, is used to improve ink penetration and spreading on offset coated media, comprising cationic polymers, multivalent metal salts, and organic acids, which helps in stabilizing the ink on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aqueous inkjet ink is printed directly on offset coated media, then the printing process is simple, but the image quality deteriorates due to non-uniform color deposition, mottle, and white streaks
Solution Approach 1:
The patent applies a pretreatment composition to the offset coated media before printing with aqueous inkjet ink. This preliminary action modifies the media surface to improve ink absorption and eliminate image defects such as mottle and white streaks, while maintaining a relatively simple overall printing process.
2Reliability
If a primer is used to treat offset coated media before printing, then ink absorbency improves, but dot gain decreases leading to white space and white lines in printed images
Solution Approach 1:
The patent uses a pretreatment composition with specific chemical parameters (pH, ionic composition, polymer content) that differ from conventional primers. This composition provides optimal ink absorption without excessive dot gain by carefully balancing the chemical properties to match the requirements of aqueous inkjet inks on offset coated media.
3Reliability
If conventional primer is applied to offset coated media, then ink fixation improves, but ink spreading is restricted causing insufficient dot spread and white lines
Solution Approach 1:
The pretreatment composition is a composite material containing multiple components including polymers, surfactants, and buffering agents in specific ratios. This composite formulation provides both ink fixation and adequate dot spread by combining materials with complementary functions that conventional single-purpose primers cannot achieve.
4Ease of operation
If aqueous inkjet ink is used on offset coated media, then the printing process is straightforward, but drying time increases leading to inter-color bleed
Solution Approach 1:
The pretreatment composition is applied before printing to modify the media surface properties, creating a substrate that accelerates ink drying. This preliminary modification reduces drying time and prevents inter-color bleed while maintaining the simplicity of the aqueous inkjet printing process.
5Shape
If the hydrophobic coating on offset media is maintained for smoothness and gloss, then surface quality improves, but ink wetting and spreading are reduced causing puddling
Solution Approach 1:
The pretreatment composition acts as an intermediary layer between the hydrophobic offset coated media and the aqueous inkjet ink. This intermediate layer modifies the surface properties to enable proper ink wetting and spreading while preserving the underlying smooth and glossy surface characteristics of the offset coated media.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances image quality by reducing mottle and inter-color bleed, improving ink coverage and spreading, and maintaining higher optical density without white streaks, resulting in better print quality on low porosity media.
Implementation Method 1
Most of the primers were designed to precipitate or aggregate the ink drops instantly by electrostatic interaction to fix the ink drop in place to prevent coalesces of multiple ink drops.
Implementation Method 2
An inkjet printing fluid set comprising: (a) an aqueous pretreatment composition comprising an ink-aggregating agent, an ink-nonaggregating polymer, and a surfactant
Implementation Method 3
The resultant low porosity means less channels for the ink vehicle to access which results in a greater dependency on ink drying by evaporation.
Implementation Method 4
The resultant low porosity means less channels for the ink vehicle to access which results in a greater dependency on ink drying by evaporation.
Data Source
AI summary
The present disclosure provides an ink fluid set containing an aqueous pretreatment composition and an aqueous inkjet ink. This ink fluid set is particularly suitable for printing on offset coated media.